GT4 or modded Cayman R
Discussion
Two comments.
It was my understanding that KW haven't offered custom valving on their V3 dampers for a while now. If you now want custom options you need to plump for the competition stuff which they will do in valving appropriate for a spring rate you like. The V3 type stuff can still be rebuilt by KW but nothing more. You are fixed with the spring rates they have allocated to the package.
I have covered this before but the limiting factor with respect to modern Porsche suspension is that there is only a small amount of travel available. Run huge amounts of droop and you can start to do really clever things with suspension. Just look at the WRC stuff for an example of what can be done when you have a large travel range. Its incredible from an engineering perspective.
Anyone coming at suspension options on modern Porsche sports cars are limited by the same lack of travel as everyone else. By bumping up the ride height there can be some opportunity to gain extra travel but thats not without significant compromise either.
The other aspect of the suspension set up, and its particularly relevant to the Boxster and Cayman because it runs struts at the rear also, is that as soon as the lower control arm moves past horizontal you lose camber. You don't need to get that low in terms of ride height for this to happen, nor do you need much suspension compression for it to happen.
So now you have limited suspension movement, plus for the box/cayman a compression limitation with respect to camber loss working to limit what you can do on the car.
Its simple to work around if you want maximum performance. Once you require comfort and improvements in control it gets tricky very quickly since theres little in the way of scope for differing approaches. Your spring is what its all about after all. The damper just controls the spring.
It was my understanding that KW haven't offered custom valving on their V3 dampers for a while now. If you now want custom options you need to plump for the competition stuff which they will do in valving appropriate for a spring rate you like. The V3 type stuff can still be rebuilt by KW but nothing more. You are fixed with the spring rates they have allocated to the package.
I have covered this before but the limiting factor with respect to modern Porsche suspension is that there is only a small amount of travel available. Run huge amounts of droop and you can start to do really clever things with suspension. Just look at the WRC stuff for an example of what can be done when you have a large travel range. Its incredible from an engineering perspective.
Anyone coming at suspension options on modern Porsche sports cars are limited by the same lack of travel as everyone else. By bumping up the ride height there can be some opportunity to gain extra travel but thats not without significant compromise either.
The other aspect of the suspension set up, and its particularly relevant to the Boxster and Cayman because it runs struts at the rear also, is that as soon as the lower control arm moves past horizontal you lose camber. You don't need to get that low in terms of ride height for this to happen, nor do you need much suspension compression for it to happen.
So now you have limited suspension movement, plus for the box/cayman a compression limitation with respect to camber loss working to limit what you can do on the car.
Its simple to work around if you want maximum performance. Once you require comfort and improvements in control it gets tricky very quickly since theres little in the way of scope for differing approaches. Your spring is what its all about after all. The damper just controls the spring.
fioran0 said:
Two comments.
It was my understanding that KW haven't offered custom valving on their V3 dampers for a while now. If you now want custom options you need to plump for the competition stuff which they will do in valving appropriate for a spring rate you like. The V3 type stuff can still be rebuilt by KW but nothing more. You are fixed with the spring rates they have allocated to the package.
I have covered this before but the limiting factor with respect to modern Porsche suspension is that there is only a small amount of travel available. Run huge amounts of droop and you can start to do really clever things with suspension. Just look at the WRC stuff for an example of what can be done when you have a large travel range. Its incredible from an engineering perspective.
Anyone coming at suspension options on modern Porsche sports cars are limited by the same lack of travel as everyone else. By bumping up the ride height there can be some opportunity to gain extra travel but thats not without significant compromise either.
The other aspect of the suspension set up, and its particularly relevant to the Boxster and Cayman because it runs struts at the rear also, is that as soon as the lower control arm moves past horizontal you lose camber. You don't need to get that low in terms of ride height for this to happen, nor do you need much suspension compression for it to happen.
So now you have limited suspension movement, plus for the box/cayman a compression limitation with respect to camber loss working to limit what you can do on the car.
Its simple to work around if you want maximum performance. Once you require comfort and improvements in control it gets tricky very quickly since theres little in the way of scope for differing approaches. Your spring is what its all about after all. The damper just controls the spring.
Neil - the ExeTC system suggests using a softer spring with their dampers as the tyre remains in better contact with the road. I'd have thought that this would have the added benefit of improving the ride comfort as well as sharpening up the handling. Is this correct?It was my understanding that KW haven't offered custom valving on their V3 dampers for a while now. If you now want custom options you need to plump for the competition stuff which they will do in valving appropriate for a spring rate you like. The V3 type stuff can still be rebuilt by KW but nothing more. You are fixed with the spring rates they have allocated to the package.
I have covered this before but the limiting factor with respect to modern Porsche suspension is that there is only a small amount of travel available. Run huge amounts of droop and you can start to do really clever things with suspension. Just look at the WRC stuff for an example of what can be done when you have a large travel range. Its incredible from an engineering perspective.
Anyone coming at suspension options on modern Porsche sports cars are limited by the same lack of travel as everyone else. By bumping up the ride height there can be some opportunity to gain extra travel but thats not without significant compromise either.
The other aspect of the suspension set up, and its particularly relevant to the Boxster and Cayman because it runs struts at the rear also, is that as soon as the lower control arm moves past horizontal you lose camber. You don't need to get that low in terms of ride height for this to happen, nor do you need much suspension compression for it to happen.
So now you have limited suspension movement, plus for the box/cayman a compression limitation with respect to camber loss working to limit what you can do on the car.
Its simple to work around if you want maximum performance. Once you require comfort and improvements in control it gets tricky very quickly since theres little in the way of scope for differing approaches. Your spring is what its all about after all. The damper just controls the spring.
Trev450 said:
fioran0 said:
The V3 type stuff can still be rebuilt by KW but nothing more. You are fixed with the spring rates they have allocated to the package.
Neil, I didn't have any problems in requesting 'non package' spring rates for my Clusports. Trev450 said:
Neil, I didn't have any problems in requesting 'non package' spring rates for my Clusports.
Did your non package spring rate require the damper to be revalved though? How long ago did you get them?You used to be able to get the V3 etc revalved to match any rate you liked but they stopped doing this. My info was that users could only get it done on the competition line of products from that point on. If they still offer this on the Clubsports then thats good for end users but surely the V3 has even less appeal if thats the case.
J-P said:
juansolo said:
Tow bar on the M and get a Caterham 
It's sooo tempting but it would hardly ever get used in reality. The thing with the CR or GT4 is that you can still use them for shopping, driving to the station, driving long distances etc. Mrs. Will still get in it, if we're going out. With a Caterham it'd be just me all the time and track days only. Spend the money instead on a Caterham. I guarantee you'll never look back.juansolo said:
J-P said:
juansolo said:
Tow bar on the M and get a Caterham
It's sooo tempting but it would hardly ever get used in reality. The thing with the CR or GT4 is that you can still use them for shopping, driving to the station, driving long distances etc. Mrs. Will still get in it, if we're going out. With a Caterham it'd be just me all the time and track days only. Spend the money instead on a Caterham. I guarantee you'll never look back.fioran0 said:
Trev450 said:
Neil, I didn't have any problems in requesting 'non package' spring rates for my Clusports.
Did your non package spring rate require the damper to be revalved though? How long ago did you get them?You used to be able to get the V3 etc revalved to match any rate you liked but they stopped doing this. My info was that users could only get it done on the competition line of products from that point on. If they still offer this on the Clubsports then thats good for end users but surely the V3 has even less appeal if thats the case.
Edited by Trev450 on Monday 5th January 09:50
J-P said:
juansolo said:
J-P said:
juansolo said:
Tow bar on the M and get a Caterham
It's sooo tempting but it would hardly ever get used in reality. The thing with the CR or GT4 is that you can still use them for shopping, driving to the station, driving long distances etc. Mrs. Will still get in it, if we're going out. With a Caterham it'd be just me all the time and track days only. Spend the money instead on a Caterham. I guarantee you'll never look back.You know it makes sense
Here you go, here are two that are pretty much spot on for your needs.
http://www.pistonheads.com/classifieds/used-cars/c...
http://www.pistonheads.com/classifieds/used-cars/c...
I wouldn't bother getting a road one if you're wanting to track. It'll compromise it for track use and you'll never use it on the road if you make it into a track car. As race cars these will be tough, well looked after mechanically (race cars tend not to be that pretty...) and have the bits on you want (dry sump, track suspension, quick rack, 6 speed, LSD, cage). Also potential there also for much more power and toys (sequential box) as the obsession kicks in. Again, modding a Caterham properly, unlike a road car, is not considered a bad thing.
You will not drive a more capable or better suited track day car than a Caterham IMO. Initial outlay aside, the residuals are very strong, you look after it and you're not going to lose a lot. Nothing responds on a circuit like them. All road cars will seem soft and unresponsive in comparison. Running costs are pennies. They're so light on consumables it's untrue and anyone can look after them with a small amount of mechanical knowledge. Finally if you stack it, they're not that expensive to repair and you haven't just trashed a very nice Porsche.
All it has against it is that it'll take up space in your garage (Brian James Minno or the like for a trailer and it can live on that in a single garage). Otherwise, no tax, no test, no MOT and it's an awesome toy to play with even when you're not driving it. Hook up, do trackday, bring it home, stick it in the garage.
Honestly, before you blow knocking on £20k on upgrades, hire an R300 race car from Bookatrack for a day and at least try the alternative.
EDIT: trying not to seem like an advert for Caterham. I've driven most of them, and owned/ran a few Westfields (not recommended unless you really know what you're doing with them so you don't get a clunker) and god I miss them. Nothing comes close. Nothing at all. Here is a more road focussed one, but he totally nails the appeal of them: https://www.youtube.com/watch?v=JAwNfgvF_Ww&sp...
I'll have another at some point, but I won't sell the Cayman to do so
That serves another role.Edited by juansolo on Monday 5th January 09:52
While you know I'm a great fan of Caterhams juansolo, I suspect you don't have to submit your choices to a higher authority as some of us do.
That said, unless you are doing a lot of track days I wouldn't BUY a Caterham for the track - I'd hire them from Bookatrack as Juansolo suggests in the offseason when they are ridiculously good value. An R300 is an ideal track day weapon - fast enough to be interesting without being at all scary. That's what I'm doing - it's a far better track day car than a Cayman. The expression you WEAR a Caterham, but DRIVE other cars is spot on.
I probably wouldn't mod a Cayman for the road either - but might have in my younger days, so I'm not going to knock it.
That said, unless you are doing a lot of track days I wouldn't BUY a Caterham for the track - I'd hire them from Bookatrack as Juansolo suggests in the offseason when they are ridiculously good value. An R300 is an ideal track day weapon - fast enough to be interesting without being at all scary. That's what I'm doing - it's a far better track day car than a Cayman. The expression you WEAR a Caterham, but DRIVE other cars is spot on.
I probably wouldn't mod a Cayman for the road either - but might have in my younger days, so I'm not going to knock it.
I'd love a Caterham, I really would but I can't justify one. I'd never use it enough. If Caterham track days are in my future, it will be rentals through bookatrack.
Spoke with Dom at SVP this afternoon. I have a test drive of their car booked for 19th January, which I'm looking forward to. Dom is very confident that I'll find it pretty mind blowing.
Spoke with Dom at SVP this afternoon. I have a test drive of their car booked for 19th January, which I'm looking forward to. Dom is very confident that I'll find it pretty mind blowing.
J-P said:
Neil - the ExeTC system suggests using a softer spring with their dampers as the tyre remains in better contact with the road. I'd have thought that this would have the added benefit of improving the ride comfort as well as sharpening up the handling. Is this correct?
Sorry for not getting back to you on this before now. A softer spring does indeed help maintain better contact with the road. With a softer spring a wheel can move vertically in response to changes in surface with more ease and this is good for both traction and comfort.
The softer a spring, the less the vertical load on a tire changes as the road surface changes or as a car corners. A tire pushed up by a bump does not have to lift as much of the chassis weight with a softer spring, while during cornering weight transfer is taken by the spring rather than passed to the tire as vertical force. This is generally good since grip and vertical load are related. While lateral grip increases with increasing vertical force, it does so with reducing effect as vertical load reduces the tires friction coefficient.
For handling however.... With softer springs comes greater body roll and pitch. This creates problems maintaining optimal suspension alignment, introduces bump steer and camber loss etc as a result of the large amount of suspension travel required. One may also in certain situations run out of room to allow the required suspension travel. This will create a situation where the wheel becomes coupled to the chassis and all vertical force is now transferred to the tire (see above for why this is bad along with rate of weight transfer below).
Having the chassis wallow around is also not good for handling since it allows forces to build up before being applied. In order to avoid all of these problems a harder spring is better.
Suspension stiffness also dictates the rate of weight transfer. The faster it is transferred the more responsive the car feels. Stiffer suspension increases the rate of this transfer though as stiffness increases, the skill required to handle the rate of transfer increases. In the Cups, stuff happens FAST as a result of the hard suspension settings.
Hopefully you can see the conflicts that are starting to arise here
Theres also the issue of dynamic weight transfer to consider (and roll couple) and how it impacts grip. Spring rates dictate how much of the dynamic load changes are passed to the tire. Increasing a spring rate prevents excessive suspension movement during dynamic weight transfer (preventing loss of alignment or introduction of unwanted effects) but increases the amount of vertical load applied to that tire. The tire is increasingly less able to transfer this load to grip. This is why stiffening the front of a car creates understeer. One needs to then select spring rates while considering the over all balance available while also keeping in mind the points above.
Tire temps are crucial to their performance and spring rates impact these (along with alignment which is also impacted by spring rate via travel). Increasing vertical load will increase the tire temp and thus the grip offered by the material but at some point the temp may become too high and grip from the tire is lost. But whats the relationship between tire temp and the rest of the factors above? You could increase temp by adjusting the spring giving more grip from the tire material but lose grip overall due to the changes to above factors. Likewise you could reduce temp by softening springs, losing tire grip itself but increase grip over all.
Aero is also impacted by excessive body movement. The more it moves the more aero is changed so one needs hard springs if one wants to control ride height changes and aero impacts. Aero can mostly be ignored for road cars but its worth a mention.
Once you think you have all of this sorted out, the real world decides to intervene and anything you do to solve one aspect changes everything else in some way.
Welcome to the world of suspension
Edited by fioran0 on Tuesday 6th January 15:52
Im going to get geeky for a moment.
Theres an interesting thing happens with suspension when a wheel loses contact with the ground.
When this happens the effective spring rate on the axle - being twice the actual spring rate when both wheels are on the ground - is cut in half. The effect of this is that the side that is under load suddenly sees increased suspension travel. Whatever the travel length has been immediately doubles and the car feels like it is falling over. When the wheel this is off the ground re-establishes contact this reverses and the car jumps up at the loaded corner.
This is why race cars run dual springs though most people think its to prevent spring dislocation at full droop. The softer spring is set so that its blocked (i.e. fully compressed) at static ride height. It sits there, in effect waiting, for large negative travel. When it occurs the soft spring becomes active responding rapidly to changes in load and hopefully keeping the tire in contact with the ground. Theres no need to worry about dislocation at full droop because an appropriate spring length is selected for the required ride height.
Aftermarket coilovers miss a trick in this regard. They simply run second springs purely to prevent dislocation. It lets a single spring length be used across a variety of settings, components and ride heights and nothing more. The rate is so low that its effectively zero.
FWIW, i run a modified approach to the dual spring set up on my project 996 (as I do on my my other Cups for bumpy tracks). The second, softer spring is selected so that it is not blocked at static ride height but instead has a small amount of travel left. This lets the car ride on a soft spring to absorb small bumps etc and in slow speed corners apply power earlier. In high speed situations or in situations with large dynamics (i.e. braking) the main (hard) spring rate is used as the softer spring is either blocked or blocks instantly. Its highly effective at helping with some of the compromises identified in my post above but requires careful set up and design. I know a few big name GT class teams that adopt this same approach. (theres little new to be done with a shock and a spring after all, just simply things that are more or less common)
This approach should not be confused with simply stacking two springs together as is more commonly seen. In this situation neither of the springs are designed to ever block transferring the combined rate to the single rate of the unblocked spring. They simply work together continuously as a single spring and create a new rate based on the equation: (rate 1 x rate 2) / (rate 1 + rate 2)
Theres an interesting thing happens with suspension when a wheel loses contact with the ground.
When this happens the effective spring rate on the axle - being twice the actual spring rate when both wheels are on the ground - is cut in half. The effect of this is that the side that is under load suddenly sees increased suspension travel. Whatever the travel length has been immediately doubles and the car feels like it is falling over. When the wheel this is off the ground re-establishes contact this reverses and the car jumps up at the loaded corner.
This is why race cars run dual springs though most people think its to prevent spring dislocation at full droop. The softer spring is set so that its blocked (i.e. fully compressed) at static ride height. It sits there, in effect waiting, for large negative travel. When it occurs the soft spring becomes active responding rapidly to changes in load and hopefully keeping the tire in contact with the ground. Theres no need to worry about dislocation at full droop because an appropriate spring length is selected for the required ride height.
Aftermarket coilovers miss a trick in this regard. They simply run second springs purely to prevent dislocation. It lets a single spring length be used across a variety of settings, components and ride heights and nothing more. The rate is so low that its effectively zero.
FWIW, i run a modified approach to the dual spring set up on my project 996 (as I do on my my other Cups for bumpy tracks). The second, softer spring is selected so that it is not blocked at static ride height but instead has a small amount of travel left. This lets the car ride on a soft spring to absorb small bumps etc and in slow speed corners apply power earlier. In high speed situations or in situations with large dynamics (i.e. braking) the main (hard) spring rate is used as the softer spring is either blocked or blocks instantly. Its highly effective at helping with some of the compromises identified in my post above but requires careful set up and design. I know a few big name GT class teams that adopt this same approach. (theres little new to be done with a shock and a spring after all, just simply things that are more or less common)
This approach should not be confused with simply stacking two springs together as is more commonly seen. In this situation neither of the springs are designed to ever block transferring the combined rate to the single rate of the unblocked spring. They simply work together continuously as a single spring and create a new rate based on the equation: (rate 1 x rate 2) / (rate 1 + rate 2)
Edited by fioran0 on Tuesday 6th January 15:53
Thanks for the above, Neil. All very interesting and leads me to the conclusion that I definitely need expert help in this area.
On a separate note SVP is thinking about being able to have a brake bias box.
What is brake bias? I won't be racing the car but wondered whether or not it would add to the experience? Does it mean changing the braking force applied to each axle? If so, does that mean you need to amend for every corner?
Thanks
On a separate note SVP is thinking about being able to have a brake bias box.
What is brake bias? I won't be racing the car but wondered whether or not it would add to the experience? Does it mean changing the braking force applied to each axle? If so, does that mean you need to amend for every corner?
Thanks
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